Commercial crops

English or Persian Walnuts. Walnuts are produced in more countries than any of the other tree nuts but production figures are unrehable. The United States is the leading producer of walnuts, at 234,913 t in 1990—1991 (valued at 279,720,000). Production, mostly in Califomia and Oregon, is nearly one-half of the world total. Many countries produce substantial quantities of walnuts. The USDA considers estimates of the commercial crop more rehable than the total yearly production figures, which in 1990—1991 were 152,500 t in China, 66,000 t in Turkey, 17,000 t in India, 13,000 t in Prance, and 12,000 t in Italy. Walnuts, both in-sheU and shelled, may be imported from many countries, eg. Prance, Italy, China, Turkey, and India. Most imported walnuts are smaller than domestic walnuts and are used by the confectionery and baking industries. 

The problems with jojoba as a commercial crop are the usual ones of domestication and cultivation. It is a slow-growing plant, available only in the wild and therefore has very wide genetic variabiUty. Efforts are underway to select the most promising variants and cultivate these as a crop in the southwestern United States deserts (7). A possible alternative for producing jojoba oil is to culture plant embryos in bioreactors (see Cell culture technology). 

Chlorinated anilines are produced by the reduction of PCNB that is used as a fungicide against a variety of commercial crops. The transformation of PCNB has been examined with a methanogenic enrichment culture from contaminated sediment, although this contained neither PCNB nor its reduction product pentachloroaniline (PCNA). The culture not only reduced the initial PCNB, but also carried out sequential dechlorination to tetra-, tri-, dichloroanilines, and ultimately to 3- and 4-chloroaniline (Tas and Pavlostathis 2005). 

Avermectin (Avid ) is a prodnct nsed in commercial crop production. The chemical is produced by bacteria and is used to control leafminers and spider mites. Sodium aluminofluoride or cryolite (Kryocide ) has been used for many years in organic crop production. This product is used to control several types of insects on a wide variety of crops. 

The castor plant is widely considered to be a nuisance plant, because it proliferates rapidly in poor, depleted soils that cannot sustain other more important commercial crops. It spreads quickly as a weed, and in some places has been listed as an intrusive species to be eliminated [51, 52]. Nevertheless, in recent years the industrial volume of castor oil has increased dramatically, driven primarily by the global interest in renewable resources for fuel and feedstocks as an alternative to petrochemicals. The majority of the volume growth has come from the Asian continent, primarily from India, where the castor plant is harvested commercially [53]. In addition to its direct use in pol3mrethane products, the oil and its components have been the focus of innovative new derivatization strategies to improve their properties for use in plastics, while retaining high levels of renewable content in the final products. These developments will be described in Section 4.5. 

As the acid number increased from 0.19 to 0.24, foliage injury increased to 40% of the entire leaf area. Forty per cent injury was considered to constitute complete economic loss in terms of commercial crop production. Based on this relationship, an acid number of 0.15 to 0.17 may be consider the threshold between slight or no injury and economic injury. 

Diphenyl ether herbicides. The diphenyl ether class of herbicides belongs to a broader area of herbicides known as protoporphyrinogen oxidase (Protox) herbicides [20,21], Diphenyl ether herbicides were initially introduced over four decades ago in the 1960s with the discovery of nitrofen by Rohm and Haas (now Dow AgroSciences) [22] and bifenox by Mobil [23], These early diphenyl ether herbicides did not attain a significant role in the control of weeds in commercial crops until the 1970s, with the introduction of the trifluoromethyl compounds oxyfluorfen [24] and acifluorfen-sodium [25], Replacement of the chlorine with a trifluoromethyl group resulted in a dramatic increase in the herbicidal properties of these compounds, in terms of both potency and the spectrum of weeds controlled. 

Because of the productivity demanded in modem agriculture to feed the millions of increasing world population, the use of different pesticides has become a necessity to contain a host of crop and household pests. A major benefit of pesticides is their ability to contain hosts of pests on commercial crops, food crops, lawn, and turf in and around household surroundings. Hop destruction by locust infestation in Africa is an example. Insecticides also are used for control of vector-bome diseases such as typhus and malaria. 

With the end of the Gvil War, the importance of hemp as a commercial crop declined. Emancipation of the slaves cut into the number of laborers harvesting hemp. More importantly, the invention of the cotton gin gave cotton a decided economic advantage over hemp and flax. The development of cheap wood pulp reduced the need for hemp as a source of paper, although it was still used in the manufacture of cigarette papers, money and Bibles. 

In the vineyard, nitrogen must be fixed into the soil naturally. This is done by planting leguminous crops such as clovers or beans between the vines. These plants have bacteria living on their roots that fix nitrogen from the air. When the plants are dead, they are ploughed in, decay and release nitrogen into the soil. At some wineries, commercial crops such as strawberries are rotated in, which add to the profitability of the vineyard. 

It is conceivable that changes in the (induced) volatile production in commercial crops could lead to the development of biological control packages in which biological control agents trained specifically for the modified crop are included. It will be exciting to see whether these approaches can lead to plants with altered (improved) predator behavior and to crops with improved biological control. 

Cuphea. Cuphea plants furnish seeds with oils that may be rich in Cg, Cjo, C12, or Ci4 acids. They generally contain >30% of oil and are expected to produce a commercial crop in the period 2005-2010. Problems of seed dormancy and seed shattering have already been solved. As markets for lauric oils already exist, there should be no difficulty in substituting cuphea oUs. More recently, it has been reported that cuphea will be used as a commercial source of lauric acid from 2003 onward (30, 102, 103). Pandey et al. (104) have described the oil (17-29%) from Cupea procumbens containing 89-95% of decanoic acid. See also Section 9.2. 

Honesty seed oil (Lunaria biennis) is characterized by its high levels of monoene acids, including 18 1 (23%), 22 1 (46%), and 24 1 (23%). It is being developed as a commercial crop for nutritional research based on its significant level of nervonic acid (24 1) (120). 

Oils containing epoxy acids Several natural epoxy acids are known, but vernolic acid (12,13-epoxyoleic) is the most common and occurs at high levels in several seed oils. Of these, serious attempts are now being made to develop Vernonia galamensis (73-78% vemolic acid) and Euphorbia lagascae (57-62% vernolic acid) as commercial crops (198). Several potential uses of this acid and the seed oils in which it occurs are being explored. 

The processing of soybeans has been described in more detail elsewhere than can be done here (132-134). Oil is recovered today by either mechanical means or through the use of organic solvents. In the preindustrial revolution period, soybeans were merely pressed with lever or animal-driven screw-operated batch presses. Around the turn of the Twentieth Century, when soybeans became a viable commercial crop in the United States, steam-powered hydraulic batch presses were used. Today, electric-powered continuous screw-presses, often referred to as expellers (but this is a trademarked name for screw presses manufactured by one supplier), or continuous countercurrent solvent extractors are used. 

Sea buckthorn is native to Asia and Europe. It is a hardy plant that is also being considered as a major commercial crop in Canada. It has been used in Tibetan, Mongolian, and Chinese traditional medicine for more than 1000 years, and has demonstrated many beneficial health attributes (6). The fruit has a good flavor and is rich in nutrients. The whole berries contain a higher concentration of... 

Cloned herbicide resistant ALS genes have been used to transform both homologous and heterologous plant species. ALS genes can be modified in vitro in order to achieve selective resistance toward broad or narrow classes of inhibitors. The modified genes can be introduced into a variety of commercial crops. 

Erickson, H.T. etal. 1984. Guarana PomI-linia cupand) as a commercial crop in Brazilian Amazonia Economic Botany 38(3) 273-286. 

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